In recent years, in hospitals and clinics or for home medical care, optical measurement apparatuses are often used as an apparatus for POCT (Point of Care Testing), which is the testing by people other than laboratory professionals. Examples of such optical measurement apparatuses include a clinical laboratory test apparatus (see e.g. Patent Document 2) for optically reading an urine test strip dipped in and pulled out of urine (see e.g. Patent Document 1) or a biochemical test piece to which blood serum/blood plasma extracted from blood is applied, and an apparatus for measuring a cuvette (see e.g. Patent Document 3) in which a liquid reagent is sealed.
FIG. 7 shows an example of conventional optical measurement apparatus (see e.g. Patent Document 4). To the illustrated optical measurement apparatus X, a test instrument Y for immunochromatography is mounted. The test instrument Y is a test piece in the form of a strip provided with a porous carrier 91. The porous carrier includes a plurality of reagent retaining portions 92 which retain a reagent (an immunologic substance, mainly an antibody) fixed to the portion. When a liquid sample such as blood or urine to be analyzed is applied to part of the test instrument Y, the sample infiltrates into the porous carrier 91. When the sample moving through the carrier reaches the reagent retaining portions 92, the sample reacts with the reagent. As a result, the reagent retaining portions 92 develop a color in accordance with the concentration of a particular component contained in the sample.
FIG. 8 shows a typical urine test strip to be used by dipping in urine. The illustrated test strip 910 includes a base 911 in the form of a strip, and reagent retaining portions 912. Each reagent retaining portion 912 is provided on the base 911 and includes a carrier made of a porous matrix such as filter paper in which a reagent is fixed in an impregnated and dried state. When the reagent retaining portion 912 of the test strip 910 is dipped in a urine sample collected in e.g. a paper cup and pulled out, the urine sample infiltrated in the reagent retaining portion 912 through the carrier reacts with the reagent. After the lapse of a predetermined reaction period, the color development of the reagent retaining portion 912 is checked.
FIG. 9 shows an example of conventional optical measurement apparatus for the measurement of a biochemical test piece including a reagent retaining portion to which a sample of urine or blood serum/blood plasma extracted from blood is to be directly applied. The illustrated optical measurement apparatus 920 includes a table 922 on which biochemical test pieces 921 are to be mounted. Each test piece 921 includes a carrier made of at least one of a high polymer compound (e.g. paste represented by water-soluble polymer) and a porous film (such as knit fabric or nonwoven fabric). The reagent retaining portion is provided by fixing a reagent to at least one of the high polymer compound and the porous film in a dry state. To perform measurement using the optical measurement apparatus 920, a liquid sample such as blood or urine to be analyzed is directly applied to the reagent retaining portion of the test piece 921. The sample dissolves the high polymer compound forming the carrier or infiltrates into the porous film. Thus, the sample reacts with the reagent in the reagent retaining portion. After the lapse of a predetermined reaction period, the color development of the reagent retaining portion is checked.
FIG. 10 shows an example of test instrument of a cuvette type. The test instrument 930 shown in the figure includes a plurality of wells 931 and is made of e.g. a light-transmitting resin. Each of the wells 931 is used as a carrier, and a reagent retaining portion is provided by sealing a reagent in a liquid or solid state in the well 931. When a sample is put into a selected one of the wells 931 of the test instrument 930, the sample reacts with the reagent in the well 931. After a predetermined period of time, the well 931, which functions as the reagent retaining portion, develops a color in accordance with the concentration of a particular component contained in the sample. Since the well 931 transmits light, the color development is easily checked from the outside.
Referring again to FIG. 7, the optical measurement apparatus X includes a light emitting means 93 and a light receiving means 94. When the test instrument Y is mounted to the optical measurement apparatus X, an instruction to start the test is given to the controller 95 by e.g. the user's operation. The controller 95 performs the light emitting operation for lighting the light emitting means 93 and the light receiving operation for receiving the light reflected by the porous carrier 91 including the reagent retaining portion 92 at the light receiving means 94. By the signal transmission from the light receiving means 94 to the controller 95, the image data of the reagent retaining portions 92 of the porous carrier 91 are stored in the controller 95. By analyzing the image data which corresponds to the color development of the reagent retaining portions 92, the presence or absence of a particular component in the sample is determined.
Though not illustrated, when the test instrument Y is an urine test strip similar to the test strip 910 shown in FIG. 8 or a biochemical test piece, the light reflection during or after the reaction of the sample with the reagent on the surface of the reagent retaining portion 912 (sometimes called a reagent pad) is measured by an exclusive device. When the test instrument Y is of a cuvette-type similar to the test instrument 930 shown in FIG. 10, the light reflection or light transmission after the reaction of the sample with the reagent in the well is measured through the light-transmitting surface of the well.
The test results obtained by the optical measurement are outputted by an output means 96 such as a printer. Based on the output results, the user can recognize the presence or absence of a particular component in the sample.
After a sample is applied to the test instrument Y, it takes some time before the reaction progresses to such a degree that proper testing is possible, and this reaction completion period varies depending on the kind or amount of the reagent. Thus, after the sample is applied to the test instrument Y, the user needs to measure the time until the testing by e.g. the optical measurement apparatus X becomes possible. To avoid this, the optical measurement apparatus shown in FIG. 9 is designed to automatically perform the pipetting, i.e., application of the sample to the test piece 921, the measurement of time and the measurement of the color development after the lapse of the reaction time. Thus, the user just needs to put an unused test piece 921 and a container containing a sample into the optical measurement apparatus 920.
However, in e.g. a simple measurement apparatus without a pipetting function or a small measurement apparatus in which a sample obtained from a patient is not to be stored, the test instrument Y does not automatically apply the sample to the test instrument Y. To use such a measurement apparatus, as described above, the user needs to apply the sample to the test instrument Y manually (by dipping in the case of a urine test strip or dropping using a pipette in the case of a test piece or a cuvette) and then mount the test instrument Y to the measurement apparatus. To manually apply the sample to the test instrument Y and further measure the time is a burden on the user.
For instance, tests for influenza by immunochromatography may need to be performed with respect to a large number of patients in one hospital in a short period of time. In such a case, samples obtained from the large number of patients may be applied to test instruments Y at different timings, and the reaction completion period needs to be measured with respect to each of the test instruments. Further, to smoothly perform the testing of the test instruments Y, the timing of application of the sample to each test instrument Y needs to be varied intentionally.
In tests for allergy by immunochromatography, each patient may be tested for a plurality of allergy items. In such a case, a sample obtained from one patient is applied to a plurality of test instruments Y. Since the test items to be tested by the test instruments Y differ from each other, the reaction completion period for proper testing may differ among the test instruments. Thus, while successively mounting test instruments to the optical measurement apparatus X, the user needs to measure the reaction completion period which differ among the test instruments, and such work is a burden on the user. Such problems related to the reaction time and the time of application of the sample occur also in the testing of a urine test strip, a biochemical test piece and a cuvette type test instrument.
Further, some reagents fixed to the reagent retaining portion 92 may fade or change its color to become lighter when unduly long time lapses after the color development due to the reaction with a sample. In rate assay in which the color development speed per unit time is measured, information on the time at which the color development starts is important. In this case, therefore, when the test instrument Y, to which the sample is applied, is accidentally left for a long time, proper test results may not be obtained when the test instrument X is mounted to the immunochromatography apparatus X.
Patent Document 1: International Publication WO2006/059694
Patent Document 2: JP-A-09-127120
Patent Document 3: JP-A-2001-318101
Patent Document 4: JP-A-2006-250787